Gas-phase transuranium chemistry: Reactions of actinide ions with alcoholsand thiols

The laser ablation with prompt reaction and detection method was employed t o provide a survey of same gasphase reactions of actinide (M = U, Np, Pu an d Am) and lanthanide (hl = Tb and Tm) ions, M+ and MO1,2+, with alcohols, t hiols and ethers. Particular attention was given the changing behavior in p rogressing across the actinide series beyond uranium. With alcohols, ROH, m ajor products included hydroxides and alkoxides, M(OH)(1,2)(+), M(OR)(1,2)( +), MO(OH)(+) and MO(OR)(+); these products are presumed to have resulted f rom RO-H and R-OH bond cleavage by ablated M+ and MO+. The abundance distri butions for these elementary products reflected the decrease in stabilities of high oxidation states between U and Am. Other alcohol reaction products included electrostatically bonded adducts, such as HO-Np+... C3H7OH, sigma -bonded organometallics, such as HO-Pu+-C2H5, and pi-bonded organometallics , such as Np+-eta(3)-{C3H5}. In view of the inability of actinide and lanth anide ions to dehydrogenate alkanes, the exhibition of dehydrogenation of t he alkyl chain of alcohols, as in HO-Pu+-C3H5O from propanol, suggests a no n-insertion mechanism involving complexation of the reactant ion to the alc ohol. Whereas O abstraction products from ROH were obfuscated by directly a blated MO1,2+, S abstraction from thiols, RSH, was manifested by the appear ance of MS+, MS2+ and MOS+. In analogy with OH abstraction from alcohols to produce metal hydroxides, SH abstraction from thiols resulted in hydrosulf ides, including Am(SH)(+) and Np(SH)(2)(+). In addition to several other re action pathways with the thiol reagents, products presumed to be thiolates included Am(C3H7S)(+) and NpO(C3H7S) from propanethiol. A primary product o f reaction with dimethyl ether were methoxides resulting from C-O bond clea vage, including Am(OCH3)(+) and Np(OCH3)(2)(+). With methyl vinyl ether, mo re complex pathways were exhibited, most of which corresponded to the elimi nation of stable organic molecules. An ancillary result was the discovery o f several small oxide clusters, Am2On+, Np2On+ and AmNpOn+. The composition s and abundance distributions of these clusters reflected the propensity of Np to exist in higher oxidation states than Am; the dominant binary cluste rs were Am2O2+ and Np2O3+. Copyright (C) 1999 John whey & Sons, Ltd.